I’ll be the first to admit I’m not making the most out of Twitter. I’m a slipshod poster at best (though in my defense, I try to live by the rule that if you don’t have anything good to post, don’t post anything at all). I’m okay with that, because in our business it’s just as important to understand the service as it is to put it to prolific use.

It goes without saying that buyers are no longer just buyers, but beacons of new interactive opportunities. Twitter (listed by Compete.com as the third largest social networking site behind Facebook and MySpace) is unquestionably one of those opportunities. We’ve watched as advertisers work their magic on the tool’s resources to create Twitter pages that not only reflect the essence of their brands but act as a direct line of contact with product advocates and potential customers. Much the same way that they use Facebook Pages as another facet of their marketing and communications efforts, they use Twitter to connect with savvy consumers in a more informal fashion.

Countless brands are doing great things with Twitter, but most fall into one of two categories with their approach. I’ll call them “organic” and “deliberate.” Both can work wonderfully well, depending on your overall marketing strategy and where Twitter fits into it. Here are two companies, each with a fiercely loyal customer base, that take a vastly different approach to using Twitter to promote their brands.

@Zappos

A fan of this e-commerce giant with great shoes and phenomenally fast shipping might never get to know Tony Hsieh. He’s Zappos.com CEO, but that’s of little value to a consumer who cares only about getting her kid’s tiny pink Crocs in time for the vacation. That is, until they spend some time with the guy on his Twitter page.

The experience will take you back to the early days of Twitter when the novelty of using the site was in sharing one’s intimate (while still suitable for public consumption) moments and life musings, all cleverly phrased to fit within 140 characters or less. Hsieh mans a Twitter CEO account, posting regularly about where he is, what he’s doing, and what he’s eating — with the occasional visual aid. He has an everyman tone that every man (and woman) can relate to; were it not for his occasional talk of celebrity-filled parties and television appearances, you’d think he was an average guy.

Of course he is, and that’s what makes him so endearing. There’s no hard sell; in fact there’s very little talk of Zappos at all (when there is it’s just as engaging, like when Hsieh pointed to a Valentine’s Day YouTube video of Zappos’ employees on the Zappos blog). There doesn’t need to be a push for products, because Hsieh is that rare species of CEO who completely embodies his brand. While reading his posts you’ll likely find yourself thinking of Zappos with the same fondness as your neighborhood bar and grill. And you’ll be just as eager to support it.

@WholeFoods

The approach that this organic foods grocery chain has taken to using Twitter is decidedly un-organic, and couldn’t be more different from that of Zappos’ CEO. Frankly, the Whole Foods Twitter page is bland and dull to read. That doesn’t matter, because Whole Foods doesn’t use Twitter to entertain. It uses Twitter to inform.

The Whole Foods strategy seems to involve answering every question submitted by its Followers — all 161,000 or so of them. If you’re a Whole Foods lover, you can actually learn a lot from reading the responses to others’ queries, along with news about new store openings and recyclable packaging information. The brand is great with keeping tweets fresh, as well as driving traffic to its Facebook Page, home to its richer promotional content.

The real reason the discussion forum approach works for Whole Foods on Twitter lies in its nature as a grocer catering to consumers with special interests and needs. A vegan who’s allergic to sunflower seeds doesn’t want to mess around with unclear package messaging; she wants to know there’s a place where she can go to get the facts. Twitter, to that consumer, is a direct link to a brand that’s entrenched in her world and a major part of her life philosophy. Knowing she can get her questions answered quickly and efficiently means a lot.

Twitter as a marketing and advertising tool is here to stay, as exemplified by Twitter’s suggestion that it may soon charge for commercial accounts and work with brands to create exclusive features. Pitch it to your clients as a complement to their display ad and Facebook campaigns. When it comes to determining a strategy for employment, though, be sure to tweet your best.